It's not quite The Texas Chain Saw Massacre, but the results of a scientific study comparing the sharpness and durability of different shark teeth sawing through prey were almost as scary.
To uncover how the shape of shark teeth affected a shark's biting and cutting ability, researchers writing in the Royal Society of Open Science conducted dynamic testing to simulate the head-shaking behaviour of large feeding sharks. Most large, predatory sharks use vigorous and rapid head-shaking to cut through prey with their teeth.
Using a reciprocating power saw, the researchers attached shark teeth to 12-inch bi-metal blades after grinding the metal teeth on the blade to a flat surface.
They then tested each set of shark teeth, including tiger sharks, bluntnose sixgill and others three times in five successive trials sawing through large chunks of salmon as prey.
Tiger and silky shark had the sharpest teeth, the researchers found. But while the tiger shark, common in Australian waters, had some of the sharpest teeth of all sharks, they blunted faster than other species.
Teeth from the bluntnose sixgill (Hexanchus griseus) showed poor cutting ability compared with tiger (Galeocerdo cuvier), sandbar (Carcharhinus plumbeus) and silky (C. falciformis) sharks, but they also showed no wear with repeated use.
"Some shark teeth are very sharp at the expense of quickly dulling, while others are less sharp but dull more slowly," wrote researchers Katherine Corn, Stacy Farina, Jeffrey Brash and Adam Summers.
Research on shark teeth by Katherine A Corn, Stacy C Farina, Jeffrey Brash, Adam P Summers Photo: Royal Society of Open Science:
While mammals have the greatest diversity in tooth morphology, the researchers said sharks were a close rival.
"Shark tooth shape is so distinctive that a single tooth can often be attributed to a particular species, especially among large predatory sharks. Though some teeth are simple triangles (eg silky shark teeth, Carcharhinus falciformis), many are spear shaped (eg mako shark teeth, Isurus oxyrinchus), deeply notched (eg tiger shark teeth, Galeocerdo cuvier) or multi-cusped (eg sixgill shark teeth, Hexanchus griseus)."
Unlike in mammals, the relationship between tooth morphology and function is not readily discernable, the researchers wrote.
The paper, Modelling tooth–prey interactions in sharks: the importance of dynamic testing, was published on August 10.
